Faber helps Montag to fix a lot of his ideas in place; before he speaks with Faber, Montag knows that something is wrong but he has no context or base from which to actualize his thoughts. Faber knows what went wrong with society because he lived through the times of censorship; Faber used to teach at a college but was forced to retire when the students stopped attending.
"I came to class at the start of the new semester and found only one student to sign up for Drama from Aeschylus to O'Neill. You see? How like a beautiful statue of ice it was, melting in the sun."
(Bradbury, Fahrenheit 451, Google Books)
The only schools left are for children, to give them the barest basics of knowledge and intellect so they can act as cogs for society's collective system. There is no need for higher learning anymore because there is no desire, no outlet for thoughts greater than those on TV. Faber understood it, but could not bring himself to fight it; Faber's understanding is crossed with Montag's uncoordinated need for action, and between them both they are able to take meaningful action.